Tom Hayes, the former Citigroup and UBS trader accused of conspiring to rig key interest rates, appeared Thursday in a London courtroom, where he faced charges of manipulating the Libor with employees at eight other financial firms.

The 33-year-old remains the only person charged by the U.K.’s Serious Fraud Office with fixing Libor, though officials said he conspired with employees from the Royal Bank of Scotland PLC (NYSE:RBS), JPMorgan Chase & Co. (NYSE:JPM), Deutsche Bank AG (NYSE:DB), Rabobank, RP Martin, HSBC PLC (NYSE:HBC) and Tullett Prebon PLC (LON:TLPR), along with colleagues at UBS AG (NYSE:UBS) and Cititgroup Inc. (NYSE:C), the Guardian reported.

The eight charges of conspiracy to defraud were split between Hayes’ stint at UBS Securities Japan from August 2006 to December 2009, and December 2009 to September 2010, when he worked for Citigroup Global Markets Japan.

Hayes and his co-conspirators allegedly made biased submissions to financial data firm Thomson Reuters (NYSE:TRI) “with the intention that the economic interests of others would be prejudiced and/or to make personal gain for themselves or another.”

The charges allege that he conspired to manipulate the yen interbank offered rates, among other interbank offered rates. These benchmark rates are known as the London interbank offered rate, or Libor, named after the city where they are set.